Israel says its forces have recovered the bodies of six hostages held by Hamas in the Gaza Strip.

In a statement, the Israel Defense Forces (IDF) said the bodies were located on Saturday in an underground tunnel in the Rafah area.

The IDF named the hostages as Carmel Gat, Eden Yerushalmi, Hersh Goldberg-Polin, Alexander Lobanov, Almog Sarusi and Master Sgt Ori Danino.

Spokesman Rear Adm Daniel Hagari said an initial assessment was they were "brutally murdered by Hamas terrorists shortly before we reached them".

After the death of Mr Goldberg-Polin - an American citizen - was confirmed, US President Joe Biden said he was "devastated and outraged" by the news.

A group representing the families of those held hostage in Gaza has demanded that Israel's Prime Minister Benjamin Netanyahu "address the nation and take responsibility for abandoning the hostages".

The Hostages Families Forum said that all six held captive were "murdered in the last few days, after surviving almost 11 months of abuse, torture, and starvation in Hamas captivity".

"The delay in signing the deal has led to their deaths and those of many other hostages," they added in a statement.

The group has also announced plans to "bring the nation to a halt" on Sunday, asking the Israeli public to join protests in Jerusalem, Tel Aviv and elsewhere in Israel to call for a hostage exchange deal.

In its statement on Sunday morning announcing the deaths, the IDF said the bodies had been "returned to Israeli territory".

"They were all taken hostage on 7 October [2023] and were murdered by the Hamas terrorist organisation in the Gaza Strip."

The statement added that their families had already been notified.

Israeli President Isaac Herzog said the "heart of an entire nation is shattered to pieces with the news" of their killing.

"On behalf of the State of Israel, I embrace their families with all my heart, and apologize for failing to bring them home safely," he added.

Meanwhile, Mr Biden said in a statement that "Hersh was among the innocents brutally attacked while attending a music festival for peace in Israel on 7 October".

"He lost his arm helping friends and strangers during Hamas’ savage massacre. He had just turned 23. He planned to travel the world.

"I have gotten to know his parents, Jon and Rachel. They have been courageous, wise, and steadfast, even as they have endured the unimaginable," Mr Biden said.

The Israeli military launched a campaign in Gaza to destroy Hamas in response to the unprecedented attack on southern Israel on 7 October, during which about 1,200 people were killed and 251 others were taken hostage.

More than 40,530 people have been killed in Gaza since then, according to the territory's Hamas-run health ministry.

US, Egyptian and Qatari mediators are trying to broker a ceasefire deal that would see Hamas release the 97 hostages still being held, including at least 27 who are presumed dead, in exchange for Palestinian prisoners in Israeli jails.

It comes as a UN-led multi-day polio vaccination campaign gets under way in Gaza, following the discovery of the potentially deadly virus in wastewater samples earlier this summer.

Three "humanitarian pauses" in the fighting - beginning on Sunday - have been agreed between Israel and Hamas so that officials can vaccinate around 640,000 children under the age of 10

The move comes after the first infection in more than 25 years was detected in a 10-month-old Palestinian child last month.